As part of the balanced military forces, Allied air and sea units continued their active defense in support of UN ground units. Beginning in late May, Fifth Air Force shifted the emphasis of its destructive effort from interdiction of communication routes to the bombing of selected industrial targets. Naval air was committed to support the FAF programs. At sea, ships steamed almost at will to sustain the U.S. lifeline. Underscoring the complete UN control of Korean waters, large naval vessels offshore fired their big guns in support of ground troops. Off both the west and east coasts, Task Force (TF) 95 maintained its blockade of North Korean ports and reduced the extent of water travel that enemy craft could safely undertake. This same naval force was responsible for the Allied defense of islands located off the east and west coasts of Korea. _Defense of West and East Coast Korean Islands_[71] [71] Unless otherwise noted, the material in this section is derived from: _PacFlt EvalRpts_ No. 4, Chap. 9; No. 5, Chap. 8; West Coast Island Defense Element ComdDs, Feb-Oct 52, hereafter _WCIDE ComdD_, with date; East Coast Island Defense ComdDs, Jan-Oct 52, hereafter _ECIDE ComdD_, with date; Col William K. Davenport ltr to CMC, dtd 27 Jun 52, Subj: Type D Report of duty as Commander West Coast Island Defense Element (CTE 95.15); Cagle and Manson, _Sea War, Korea_; Field, _NavOps, Korea_. Just off the northwest Korean mainland a string of islands extends from the mouth of the Yalu River down around the peninsula to Pusan in the southeast. Most of these islands are tiny and are located south of the 38th Parallel. Only a few lie off the east coast, and these are clustered primarily in the North Korean harbor of Wonsan. By early 1951, UN forces exercised control over most of the Korean islands. Their tactical importance is shown from their diverse use as sites for UN Command intelligence activities, USAF radar installations, locations for the emergency landing strips used by Allied planes, bases for U.S. search and rescue operations, and as springboards for possible thrusts into enemy rear areas.[72] [72] Evidence of Chinese concern about such rear area attacks is apparent in the countermeasures taken: “Order of Battle reports indicated that a total of three North Korean Corps and three Chinese Communist Armies were engaged in coastal defense operations on the east and west coasts of North Korea.” _PacFlt EvalRpt_, No. 5, p. 8-79.